This invention relates to an apparatus for preheating the material to be charged into steel making equipment.
In steel making processes, it is desirable to preheat materials such as scrap, alloy iron, directly reduced iron and lime before they are placed for example into an electric furnace.
Thus the steel making material is preheated to avoid a steam explosion accident when it is charged into the equipment for the safety of operation and to achieve an improved steel making efficiency by promoting melting of the material.
While auxiliary burners have heretofore been most widely used as means for preheating the material, such means are undesirable for the economical use of energy which is presently demanded. Accordingly a method has been introduced into use which utilizes an exhaust gas as recovered from a dust collector by which the gas generated in the furnace is forcibly withdrawn therefrom. This method nevertheless has the following drawbacks.
In addition to the basic problem that it is difficult to stabilize the pressure loss involved in the dust collector, it is impossible to adapt the method for the operation cycle of the highly advanced steel making process in which the melting time has been remarkably shortened. The known method requires the use of a large numer of buckets which, however, are serviceable only for a short period of time because they are placed directly into a preheating chamber, while such buckets must be provided with a lining or cooled with water.
Furthermore, scraps and like materials which are available in snowy or rainy districts contain large quantities of water and are prone to steam explosion accidents when charged into the equipment since it is difficult to fully dewater the materials. It is also important to provide a sealed structure for preventing heat losses.